Humidifier with a water tub within a pressurized chamber

ABSTRACT

A tub is configured to contain a supply of water and is configured to be inserted into a chamber of a humidifier. The tub includes a tub base configured to contain the supply of water. The tub also includes a tub lid and a flow plate provided between the tub base and the tub lid. The flow plate includes a water level indicator configured to indicate a level of the supply of water in the tub base. In addition, the water level indicator includes a generally rectangular portion and a generally triangular portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/223,313, filed Dec. 18, 2018, now allowed, which is a continuation ofU.S. application Ser. No. 15/856,420 filed Dec. 28, 2017, now U.S. Pat.No. 10,195,389, which is a continuation of U.S. application Ser. No.15/194,634, filed Jun. 28, 2016, now U.S. Pat. No. 10,279,141, which isa continuation of U.S. application Ser. No. 14/157,639, filed Jan. 17,2014, now U.S. Pat. No. 9,402,970, which is a continuation of U.S.application Ser. No. 12/737,926, filed Mar. 1, 2011, now U.S. Pat. No.8,631,789, which is the U.S. National Phase of International ApplicationNo. PCT/AU2009/001232 filed on Sep. 17, 2009 and which claims priorityto U.S. Applications 61/097,765, filed Sep. 17, 2008 and 61/226,134,filed Jul. 16, 2009, each of which is incorporated herein by referencein its entirety.

The entire contents of U.S. application Ser. No. 12/397,850, filed Mar.4, 2009, are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to systems and method to control thehumidity of breathable gases used in all forms of respiratory apparatusventilation systems including invasive and non-invasive ventilation,Continuous Positive Airway Pressure (CPAP), Bi-Level therapy andtreatment for sleep disordered breathing (SDB) conditions such asObstructive Sleep Apnea (OSA), and for various other respiratorydisorders and diseases.

BACKGROUND OF THE INVENTION

Respiratory apparatuses commonly have the ability to alter the humidityof the breathable gas in order to reduce drying of the patient's airwayand consequent patient discomfort and associated complications. The useof a humidifier placed between the flow generator and the patient maskproduces humidified gas that minimizes drying of the nasal mucosa andincreases patient airway comfort. In addition in cooler climates, warmair applied generally to the face area in and about the mask is morecomfortable than cold air.

Many humidifier types are available, although the most convenient formis one that is either integrated with or configured to be coupled to therelevant respiratory apparatus. While passive humidifiers can providesome relief, generally a heated humidifier is required to providesufficient humidity and temperature to the air so that the patient willbe comfortable. Humidifiers typically comprise a water tub having acapacity of several hundred milliliters, a heating element for heatingthe water in the tub, a control to enable the level of humidification tobe varied, a gas inlet to receive gas from the flow generator, and a gasoutlet adapted to be connected to a patient conduit that delivers thehumidified gas to the patient's mask.

Typically, the heating element is incorporated in a heater plate whichsits under, and is in thermal contact with, the water tub.

SUMMARY OF THE INVENTION

One aspect of the invention is a respiratory apparatus that comprises ahumidifier for humidifying a flow of breathable gas to be delivered to apatient in which a tub of the humidifier is insulated to reduce thetemperature of the water and the power consumed by the apparatus.

Another aspect of the invention is a humidifier for a respiratoryapparatus that includes a chamber that is pressurizable to reduce thepressure on joints of the humidifier tub to reduce leaks.

A further aspect of the invention is a humidifier for a respiratoryapparatus that includes a chamber that is pressurizable to reducetolerances for insertion of a tub with respect to seals on an inlet andan outlet tube of the humidifier chamber.

A still further aspect of the invention is a humidifier for arespiratory apparatus that directs air over the surface of a supply ofwater contained in a tub to humidify a flow of breathable gas regardlessof the water level.

Another aspect of the invention is a humidifier for a respiratoryapparatus that includes seals that are not under the supply of water,thus reducing a risk of leakage.

A still further aspect of the invention is a humidifier for arespiratory apparatus that prevents water from spilling back into a flowgenerator, or blower, that generates a flow of breathable gas.

Yet another aspect of the invention is a humidifier for a respiratoryapparatus that includes a tub that is disposable.

Another aspect of the invention is a humidifier for a respiratoryapparatus that includes a tub that is cleanable and/or reusable.

Still another aspect of the invention is a humidifier for a respiratoryapparatus that includes a tub that comprises a water level indicator,for example a water level indicator that indicates a maximum fill level.Yet another aspect of the invention relates to a water level indicatorthat may be heat from the tub. A still further aspect of the inventionrelates to a water level indicator in a tub that may be viewed through awindow of the humidifier. An even further aspect of the inventionrelates to a water level indicator that appears to change color as thewater level changes, for example appears to be a darker color or mixtureof colors.

Another aspect of the invention is a humidifier for a respiratoryapparatus that is connectable to a heated or non-heated tube fordelivery of the humidified flow to a patient.

A further aspect of the invention relates to a tub that is removablefrom the humidifier and is configured to prevent any water flowing outof the tub from flowing back into the flow generator.

According to a sample embodiment, a humidifier for humidifying a flow ofbreathable gas to be delivered to a patient comprises a chamberconfigured to receive the flow of breathable gas; a tub configured tocontain a supply of water, the tub being configured to be inserted intothe chamber; a lid provided on the chamber and being movable between anopen position and a closed position; and a seal provided on the lid, theseal being configured to seal the chamber such that the flow ofbreathable gas pressurizes the chamber.

According to yet another sample embodiment, a tub for insertion into ahumidifier chamber comprises a tub base configured to contain a supplyof water; a tub lid; a flow plate; and a seal connected to the flowplate, wherein the flow plate is positioned between the tub base and thetub lid via the engagement of the seal with side wall edges of the tubbase and side wall edges of the tub lid.

According to a further sample embodiment, a respiratory apparatus forproviding a humidified flow of breathable gas to a patient comprises aflow generator to generate a flow of breathable gas and a humidifierand/or a tub as described above.

According to another sample embodiment, a humidifier for humidifying aflow of breathable gas to be delivered to a patient comprises a chamberconfigured to receive the flow of breathable gas; a tub configured tocontain a supply of water, the tub being configured to be inserted intothe chamber; and a lid provided on the chamber and being movable betweenan open position and a closed position. The tub comprises a tub baseconfigured to contain a supply of water; a tub lid; and a flow plateprovided between the tub base and the tub lid, wherein the flow platecomprises a water level indicator configured to indicate a level of thesupply of water in the tub base.

According to a still further sample embodiment, a tub is configured tocontain a supply of water and to be inserted into a chamber of ahumidifier. The tub comprises a tub base configured to contain a supplyof water; a tub lid; and a flow plate provided between the tub base andthe tub lid, wherein the flow plate comprises a water level indicatorconfigured to indicate a level of the supply of water in the tub base.The water level indicator comprises a generally rectangular portion anda generally triangular portion. The generally triangular portioncomprises an angled wall that extends at least partially below the flowplate and the angled wall comprises a drain hole and indicia.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 schematically depicts of a respiratory apparatus including a flowgenerator and humidifier according to a sample embodiment of theinvention;

FIG. 2 schematically depicts the humidifier of FIG. 1 with the lid inthe closed position;

FIG. 3 schematically depicts the humidifier of FIG. 1 with the lid inthe open position;

FIG. 4 schematically depicts a partial exploded assembly view of thehumidifier of FIG. 1;

FIG. 5 schematically depicts a cradle of the humidifier of FIG. 4;

FIG. 6 schematically depicts a lid closure member of the humidifier;

FIG. 7 schematically depicts an electrical connector and tube connectorof the humidifier of FIG. 1;

FIG. 8 schematically depicts the cradle and humidifier bottom of thehumidifier of FIG. 1;

FIG. 9 schematically depicts the humidifier cradle and the humidifierbottom of FIG. 8 in an assembled configuration;

FIG. 10 schematically depicts an inner plate of the humidifier of FIG.1;

FIG. 11 schematically depicts a latch plate of the humidifier of FIG. 1;

FIG. 12 schematically depicts the humidifier of FIG. 1 including anoutlet tube;

FIG. 13 schematically depicts a sealing ring for the humidifier outlettube of FIG. 12;

FIG. 14 schematically depicts the outlet tube of the humidifier of FIG.12;

FIG. 15 schematically depicts the humidifier of FIG. 1 including theinner plate, the outlet tube, and the tube connector;

FIG. 16 schematically depicts the lid and the seal of the humidifier ofFIG. 1;

FIG. 17 schematically depicts the seal of FIG. 16;

FIG. 18 schematically depicts a side view cross section of thehumidifier of FIG. 1;

FIG. 19 schematically depicts a water tub including a tub base and aflow plate of the humidifier of FIG. 1;

FIG. 20 schematically depicts a bottom perspective view of the flowplate of FIG. 19;

FIG. 21 schematically depicts an exploded assembly of a tub, includingthe tub base and flow plate of FIG. 19, according to one sampleembodiment;

FIG. 22 schematically depicts the assembled tub of FIG. 21;

FIG. 23 schematically depicts a cross section of the tub of FIG. 22;

FIG. 24 schematically depicts a section view of the tub of FIG. 22;

FIG. 25 schematically depicts a seal between the flow plate and the tubbase of the tub of FIG. 21;

FIG. 26 schematically depicts a tub according to another sampleembodiment;

FIG. 27 schematically depicts an exploded assembly view of the tub ofFIG. 26;

FIG. 28 schematically depicts a plan view of the tub of FIGS. 26 and 27;

FIG. 29 schematically depicts a cross section along line 29-29;

FIG. 30 schematically depicts a cross section along line 30-30;

FIG. 31 schematically depicts a bottom perspective of the flow plate andthe tub lid in an assembled condition;

FIG. 32 schematically depicts a cross section of the flow plate and thetub lid of FIG. 31;

FIG. 33 schematically depicts a detailed view of the connection of theflow plate to the tub lid;

FIG. 34 schematically depicts a cross section of the tub in theassembled condition, including the tub base;

FIG. 35 schematically depicts a connection of the tub base, the flowplate, and the tub lid;

FIG. 36 schematically depicts a perspective of the tub in the assembledcondition;

FIG. 37 schematically depicts a top perspective of the flow plate;

FIG. 38 schematically depicts a bottom perspective of the flow plate;

FIG. 39 schematically depicts a plan view of the flow plate;

FIG. 40 schematically depicts a cross section along line 40-40;

FIG. 41 schematically depicts a bottom view of the flow plate;

FIG. 42 schematically depicts an assembly of the flow plate and seal;

FIG. 43 schematically depicts a plan view of the flow plate;

FIG. 44 schematically depicts a cross section along line 44-44;

FIG. 45 schematically depicts a bottom view of the flow plate;

FIG. 46 schematically depicts the maximum water level indicator of theflow plate;

FIG. 47 schematically depicts a cross section of the maximum water levelindicator on the flow plate;

FIG. 48 schematically depicts a detailed view of a wedge of the bridgeof the flow plate;

FIG. 49 schematically depicts a detailed view of the maximum water levelindicator;

FIG. 50 schematically depicts a perspective view of a tub according toanother sample embodiment;

FIG. 51 schematically depicts another perspective view of the tub ofFIG. 50;

FIG. 52 schematically depicts a top view of the tub of FIG. 50;

FIG. 53 schematically depicts an exploded assembly of the tub of FIG.50;

FIG. 54 schematically depicts an exploded assembly of the tub of FIG. 50from another perspective;

FIGS. 55a and 55b schematically depict cross sections of the tub of FIG.50;

FIG. 56 schematically depicts a perspective view of a flow plate of thetub of FIG. 50;

FIG. 57 schematically depicts another perspective view of the flow plateof FIG. 56;

FIG. 58 schematically depicts a top view of the flow plate of FIGS. 56and 57;

FIG. 59 schematically depicts a bottom view of the flow plate of FIGS.56-58;

FIGS. 60a-60c schematically depict a water level indicator usable withthe flow plate of FIGS. 56-59;

FIG. 61 schematically depicts a perspective view of the flow plate andwater level indicator of FIGS. 56-60 c with the tub lid of the tub ofFIGS. 50-55;

FIG. 62 schematically depicts another perspective view of the flowplate, water level indicator and tub lid of FIG. 61;

FIG. 63 schematically depicts an exploded assembly of a tub, includingthe tub base and flow plate of FIG. 19, according to another sampleembodiment;

FIG. 64 schematically depicts the assembled tub of FIG. 63;

FIG. 65 schematically depicts a cross section of the tub of FIG. 64;

FIG. 66 schematically depicts a section view of the tub of FIG. 64;

FIG. 67 schematically depicts a seal between the flow plate and the tubbase of the tub of FIG. 63;

FIG. 68 schematically depicts an exploded assembly of a tub according toanother sample embodiment;

FIG. 69 schematically depicts an exploded assembly of the tub of FIG. 68from another perspective;

FIG. 70 schematically depicts a perspective view of the tub of FIGS. 68and 69;

FIG. 71 schematically depicts another perspective view of the tub ofFIGS. 68 and 69;

FIG. 72 schematically depicts a section of the tub of FIGS. 68-71;

FIG. 73 schematically depicts a heated air delivery hose, tube, orconduit, including a cuff having a humidifier connector;

FIGS. 74 and 75 schematically depict the air delivery hose, tube, orconduit of FIG. 73 including a cuff to connect the hose, tube, orconduit to a patient interface, such as a mask; and

FIG. 76 schematically depicts a cross section of the hose, tube, orconduit and cuff of the FIGS. 56 and 57.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Respiratory Apparatus

Referring to FIG. 1, a respiratory apparatus 10 comprises a flowgenerator, or blower, 12 and a humidifier 14. The humidifier 14comprises a humidifier chamber 16 and a lid 18 which is pivotablebetween an open and a closed position. A water chamber, or tub, 20 isprovided in the humidifier chamber 16 and is covered by the lid 18 whenthe lid 18 is in the closed position. A seal 19 is provided to the lid18, as shown in more detail in FIG. 15. The lid 18 includes a window 30to allow visual inspection of the contents of the humidifier tub 20. Theseal 19 includes an aperture 31 that corresponds to the position of thewindow 30 of the lid 18.

The tub 20 comprises a tub lid 86 that is configured to direct a flow ofbreathable gas generated by the flow generator 12 along a channel 90 andthrough an outlet 92 of the channel 90 into the tub 20, as described inmore detail below. The tub 20 includes an outlet 88 for the humidifiedflow of breathable gas to a tube configured to deliver the humidifiedflow to a patient interface, e.g. a mask.

Humidifier

As shown in FIG. 2, the humidifier 14 is connectable to the flowgenerator 12 by connectors, or latches, 24. The latches 24 may be, forexample, spring biased latches that engage corresponding recesses (notshown) in the flow generator 12. An electrical connector 26 is providedto electrically connect the flow generator 12 to the humidifier 14.Electrical power may be provided from the flow generator 12 to thehumidifier 14, although it should be appreciated that the humidifier maybe provided with its own power source. Control signals may also beprovided from the flow generator 12 to the humidifier 14 through theelectrical connector 26.

It should be appreciated that the humidifier 14 may include its owncontrol system, for example, a microprocessor provided on a printedcircuit board (PCB). The PCB may be located in the wall of thehumidifier chamber 16 and may include a light, e.g. an LED, toilluminate the contents of the tub 20 to permit visual inspection of thewater level. Referring to FIG. 4, an aperture 35 may be provided in thewall of the humidifier chamber 16 to allow the light on the PCB toilluminate the humidifier chamber 16. The aperture 35 is covered with acover 37 to prevent access to the PCB and the light (e.g. LED) from thehumidifier chamber 16. The cover 37 may be transparent or colored toprovide a colored light, such as a green light to appear within thehumidifier chamber 16. The light is provided to shine into thehumidifier chamber 16 to allow the water level in the water tub 20 to beseen. Alternatively, multiple lights may be located on the PCB toprovide different indications regarding the heating of the humidifier,for example an amber light may be provided to indicate that thehumidifier is heating up to a required temperature and a blue light maybe provided to identify when the humidifier is at the requiredtemperature.

The humidifier 14 comprises the humidifier chamber 16 and the lid 18which is pivotally connected to the humidifier chamber 16. As shown inFIGS. 3 and 4, the lid 18 comprises a hinge portion 17 that is hinged tohinge portions 47 provided on the humidifier chamber 16. Referring toFIG. 3, a humidifier bottom 54 is provided to the humidifier chamber 16,as shown in more detail in FIG. 8. An opening member 28 is provided forreleasing the lid 18 to allow the lid to be pivoted to the open positionas described in more detail below.

Referring again to FIGS. 3 and 4, the lid 18 comprises catches 15 thatare configured to be engaged by the latches 44 to maintain the lid inthe closed position. The seal 19 also comprises wedge-shaped protrusions13 that are configured to engage the water tub 20, for example the tublid 86, when the lid 18 is in the closed position to push the tub 20 ina direction (e.g. laterally) toward an outlet 34 of the humidifierchamber 16 to assist in forming a seal between the water tub outlet 88and the humidifier chamber outlet 34. A domed portion 11 is alsoprovided on the seal 19 to push the water tub 20 against a heating plate36 when the lid 18 is in the closed position. A circular seal section,or sealing ring, 21 is also provided to the seal 19 to seal, when thelid 18 is in the closed position, a tub emptying aperture 89 provided inthe tub lid 86.

Referring again to FIGS. 2 and 4, the humidifier chamber 16 alsoincludes an air inlet 22 configured to receive the flow of breathablegas generated by the flow generator 12 when the humidifier 14 isconnected to the flow generator 12 by the latches 24. The inlet 22directs the flow into the channel 90 (see FIGS. 1, 3 and 21-24) in thetub lid 86 of the water tub 20. The flow is directed by the channel 90to the outlet 92 into the water tub 20.

As shown in FIGS. 4 and 5, the humidifier chamber 16 comprises ahumidifier cradle 32 that includes the air inlet 22. The humidifiercradle 32 also includes the humidifier chamber outlet 34 to allow thehumidified flow to be delivered to a delivery hose, tube, or conduitthat is configured to be connected to the humidifier to deliver thehumidified flow to a patient. The outlet 34 is provided in a back sideof the humidifier cradle 32. It should be appreciated that the outlet 34may be provided on a side of the humidifier cradle 32. Such amodification would also entail modifying the water tub 20 to align theoutlet 88 of the tub 20 with the outlet 34 of the humidifier cradle 32.

Referring to FIG. 4, the heating plate 36 is provided to heat the watersupply contained in the humidifier chamber 16. A cradle bottom 40 isprovided beneath the heating plate 36 and an insulation layer 38 isprovided between the heating plate 36 and the cradle bottom 40. Theheating plate 36 may be formed, for example, of a nickel chrome alloy oranodized aluminum that allows the heating plate 36 to be formed thinnerthan currently available heating plates and with a larger surface area.The heating plate 36 may also include a thermistor that is controlled bya control circuit, for example, provided on the PCB.

Referring to FIGS. 4-6, the humidifier cradle 32 supports a lid closuremember 42 that is movable between an open position and a closedposition. The lid opening member 28 is provided at an end of the lidclosure member 42 as shown in FIG. 6. The lid closure member 42comprises latches 44 that are configured to engage catches 15 of the lid18 and retain the lid 18 in the closed position. The lid closure member42 comprises a rod, or post, 48 that supports a spring 46 that biasesthe lid closure member 42 into the closed position. To open the lid 18,the opening member 28 is pushed by the user against the bias of thespring 46, to the right in FIG. 5, to move the latches 44, and the lidclosure member 42, to the open position. When the user releases the lidopening member 28, the bias of the spring 46 returns the lid closuremember 42 and the latches 44 to the closed position.

The lid closure member 42 is supported by a front retaining wall 33 ofthe cradle 32. The lid closure member 42 includes tabs 45 that engageslots 41 formed in the front retaining wall 33. The front retaining wall33 also comprises slots 39 through which the latches 44 protrude. Theslots 39, 41 accommodate sliding movement of the lid closure member 42and the latches 44 and the tabs 45, respectively, engaged with the slots39, 41.

As shown in FIG. 7, the electrical connector 26 is connected to aplurality of wires 52, for example, three wires, that are connected to atube connector 50 that is shown in FIG. 15 and described in more detailhereinafter. The tube connector 50 comprises a plurality of contacts 78that correspond in number to a number of wires 52 and are each connectedto a respective wire. Although three wires 52 and three contacts 78 areshown in the drawings, it should be appreciated that a different numberof wires and contacts may be provided, for example, two wires and twocontacts. The tube connector 50 allows for the connection of a heatedtube, for example, such as disclosed in U.S. patent application Ser. No.11/936,822, filed Nov. 8, 2007, the entire contents of which areincorporated herein by reference.

As shown in FIGS. 8 and 9, the humidifier cradle 32 is supported by achamber bottom 54 of the humidifier chamber 16. The chamber bottom 54comprises a pair of latches 56 that are configured to engagecorresponding catches (not shown) on the back of the humidifier cradle32 to secure the humidifier cradle 32 to the chamber bottom 54. Thechamber bottom 54 also includes a bottom opening 58 through which thebottom of the humidifier cradle 32 extends. The chamber bottom 54 isconfigured to cover the wires 52 and the lid closure member 42 whenconnected to the cradle 32, as shown in FIG. 8.

Referring to FIGS. 9-11, an inner plate 60 may be secured to thehumidifier cradle 32 over the latches 24 and the electrical connection26. As shown in FIG. 10 the inner plate 60 includes a plurality ofapertures 62 that are configured to allow the latches 24 to extendtherethrough and an aperture 64 configured to allow the electricalconnector 26 to extend therethrough. The inner plate 60 also comprises apair of apertures 66 that are configured to receive fasteners, forexample, threaded fasteners 80 (FIG. 15), to secure the inner plate 60to the humidifier cradle 32. A boss 68 may also be provided on the innerplate 60 to receive a fastener, for example, a threaded fastener 80 forsecuring the inner plate 60 to the humidifier cradle 32. The inner plate60 provides spillback protection to prevent water spilling back from thehumidifier 14 to the flow generator 12.

As shown in FIG. 11, the latches 24 are provided on a latch plate 23that is provided between the humidifier cradle 32 and the inner plate60. An end of the latch plate 23 is secured to a plate 25 that is alsoprovided between the humidifier cradle 32 and the inner plate 60. Theplate 25 comprises posts 29 that support springs 27 that are configuredto bias the latch plate 23 so that the latches 24 extend through theapertures 62 of the inner plate 60 in the positions shown in FIG. 9.When the humidifier 14 is connected to the flow generator 12 the latches24 engage catches (not shown) provided on the flow generator 12 and thelatches 24, and subsequently the latch plate 23, are pushed against thebias of the springs 27 (to the right in FIG. 9). Once the latches 24fully engage the catches, the springs 27 bias the latch plate 23 and thecatches 24 back to their starting position shown in FIG. 9 with thelatches 24 engaged with the catches of the flow generator 12. When thehumidifier 14 is connected to the flow generator 12, the electricalconnector 26 connects with a corresponding electrical connector (notshown) in the flow generator 12 to permit the flow generator 12 toprovide power and/or control signals to the humidifier 14. As shown inthe figures, the electrical connector 26 may comprise a terminal, orterminals, although it should be appreciated that the electricalconnector 26 may comprise a contact, or contacts, that are received interminals in the flow generator 12.

Referring to FIGS. 12-14, the humidifier cradle 32 may comprise anoutlet tube 70 provided through the outlet 34. As shown in FIG. 14, theoutlet tube 70 may comprise a flange 72 that is configured to engage theback wall 55 of the humidifier cradle 32 and a groove 74 that isconfigured to receive a sealing ring 76 shown in FIG. 13. The outlettube 70 may be removed to allow replacement of all wet area parts of thehumidifier, for example, the tub 20 and the outlet tube 70. The outlettube 70 may also be made out of a material that can be sterilized. Itshould be appreciated that the outlet tube 70 may also be disposable.

Referring to FIGS. 15 and 16, in the closed position the lid 18 providedwith the seal 19 allows the humidifier chamber 16 to be sealed andbecome pressurized by the flow generator 12 when the flow generatorgenerates a flow of air through the inlet 22 of the humidifier 14.Pressurizing the humidifier chamber 16 reduces the pressure on thejoints on the tub 20 to reduce leaks. Pressurizing the humidifierchamber 16 also reduces tolerances for insertion of the tub 20 withrespect to seals on the inlet 22 and the outlet tube 70 of thehumidifier chamber 16. The humidifier chamber 16 also insulates the tub20 to provide enhanced thermal properties and reduce power consumption.Insulating the tub 20 also reduces heat loss to the surroundings. Thehumidity output of the humidifier is determined directly from the watertemperature. As the heat loss from the tub to the surroundings isreduced due to insulating the tub, less power is needed to reach thewater temperature corresponding to a desired humidity output. Inaddition, incoming air is preheated as it passes the outside walls ofthe tub, before it enters the tub, which also reduces the power requiredto reach the water temperature corresponding to the desired humidityoutput.

As also shown in FIG. 15, the inner plate 60 is secured to thehumidifier cradle 32 by the threaded fasteners 80, although it should beappreciated that other fastening members or methods may be used tosecure the inner plate 60 to the humidifier cradle 32. It should beappreciated that other latching structures and systems may be used toreleasably secure the lid. For example, push to close and button to openoperation systems may be used. Other examples include, but are notlimited to, a rod latching system, a rotating latch or a hooking latch.

The outlet tube 70 and the tube connector 50 provide the ability toconnect both a standard tube and a heated tube. As shown in FIG. 15, thetube connector 50 and the contacts 78 are provided separately from theoutlet tube 70. A heated tube having corresponding electricalconnections, e.g. terminals, may be provided in a rotational snap fitwith the tube connection 50. This type of connection provides ease ofconnection and reduces the tolerance stack of the respiratory apparatus10. A heated tube 134 suitable for connection to and use with thehumidifier 14 is described in more detail with reference to FIG. 31. Asshown in FIG. 15, a cover 132 may be connected to the back wall of thehumidifier to cover the tube connector 50, and the contacts 78, when anon-heated tube is connected to the outlet tube 70. The cover 132 may beformed of a pliable rubber or other suitable flexible material.Alternatively the cover 132 may be a separate component not attached tothe humidifier that may be inserted over the connector 50.

Referring to FIGS. 17 and 18, the seal 19 comprises a groove 51configured to receive a corresponding edge, or rim, 57 of the lid 18 toconnect the seal 19 to the lid 18. The wedge-shaped protrusions 13 (seealso FIG. 3) are configured to engage the tub lid 86 when the lid 18 isin the closed position to bias the water tub 20 toward the back wall ofthe humidifier chamber 16 so that the outlet 88 is in sealing engagementwith the outlet tube 70. The seal 19 also comprises a sealing rim 49that extends around the perimeter of the seal 19 and is configured toseal the perimeter of the lid 18 when the lid is in the closed position.An inner sealing rim 53 is provided around the aperture 31 of the seal19 to seal around the window 30 of the lid 18.

Humidifier Tub—Disposable—First Embodiment

Referring to FIGS. 19 and 20, the water tub 20 comprises a tub base 82and a flow plate 84. The flow plate 84 comprises a dividing plate 96that comprises an inlet 98 that is configured to receive the flow ofbreathable gas directed by the channel 90 of the tub lid 86. The outlet92 of the channel 90 is configured to direct the flow into the inlet 98of the dividing plate 96 when the tub lid 86 is secured to the tub base82 as described in more detail below.

The flow plate 84 also comprises a frame or tub seal 94 that isconfigured to seal the perimeter of the tub base 82 when the tub lid 86is connected to the tub base 82. The frame seal 94 is connected to thedividing plate 96 by a plurality of supports, or bridges, 100. A gap 87is provided between the dividing plate 96 and the frame seal 94 by thebridges 100.

A water level indicator 102 is provided on the dividing plate 96 of theflow plate 84 to provide an indication of the water level. As shown inFIGS. 18-20, the water level indicator 102 may include a frusto-conicalportion. As shown in FIG. 23, the water level indicator 102 may be coneshaped. A small drain hole 104 is located in the bottom of the waterlevel indicator 102 to allow the water to fill up the water levelindicator 102 and then drain out of the bottom of the water levelindicator 102 to the tub base 82 as the water level decreases in the tubbase 82. The water level indicator 102 provides an indication of thewater level in the tub 20 by the water level indicator 102 being filledwith water once the water level in the tub base 82 reaches the level ofthe small drain hole 102, which then allows the water level in the tubbase 82 to be filled until the water in the water level indicator 102reaches the desired level such as that indicated by indicia 103.Although the water level indicator 102 provides an indication of thewater level, as the flow of breathable gas is directed to the surface ofthe water contained in the tub base 82, the water level is not criticalas the flow is in good contact with the surface of the water. The waterlevel indicator 102 may be provided with indicia 103 to indicate amaximum water level of the water tub 20. The light emitted from the PCBthrough the aperture 35 allows the water level in the water levelindicator 102 to be seen.

Referring to FIGS. 21-25, according to a sample embodiment of theinvention, the water tub 20 is configured to be disposable. The tub 20comprises the tub base 82 configured to contain a supply of water. Thetub lid 86 is provided on the tub base 82. The tub lid 86 may be securedto the tub base 82 by, for example, welding. The tub 20 may be formed,for example, of plastic material, metal or a combination of metal andplastic.

As shown in FIGS. 23 and 24, the flow plate 84 is provided on the tubbase 82. The tub lid 86 comprises the channel 90 that receives the flowof breathable gas generated by the flow generator 12 that enters thehumidifier 14 through the air inlet 22. As shown in FIG. 23, the channel90 comprises the channel outlet 92 that is received in the inlet 98 inthe dividing plate 96. The dividing plate 96 ensures that the flow ofbreathable gas flows across the whole tub as air enters into the centerand flows to the outside of the tub and then up through the gap 87between the walls of the tub base 82 and the dividing plate 96 to theoutlet 88 of the tub lid 86.

Referring to FIG. 25, the tub base 82 comprises a tub base rim 118 thatis engaged by a latch 130 of the tub lid 86 to connect the tub base 82and the tub lid 86. The frame seal 94 comprises a seal 112 that isprovided between the latch 130 of the tub lid 86 and the rim 118 at thetub base 82. A wedge 114 is provided on each bridge 100 and connected tothe seal 112 to force the seal 112 into a sealing engagement between therim 118 and a latch 130. The wedge 114 is engaged by a wedge 116 of thetub lid 86 to force the seal 112 into sealing engagement between the rim118 and the latch 130.

Humidifier Tub—Disposable—Second Embodiment

Referring to FIGS. 26-49, a humidifier tub that is configured to bedisposable according to another sample embodiment is illustrated. Thehumidifier tub 20 may comprise a tub base 82, a tub lid 86 having achannel 90. The tub lid 86 may also comprise a tub outlet 80 fordelivering a humidified flow of breathable gas. A tub emptying aperture89 may also be provided in the tub lid 86.

Referring to FIG. 27, the humidifier tub 20 may also comprise a flowplate 84 having a dividing plate 96. An inlet 98 is provided on thedividing plate 96 that corresponds to the outlet 92 (FIG. 28) of thechannel 90 of the tub lid 86. The dividing plate 96 of the flow plate 84is connected to a frame seal 94 by a plurality of bridges 100. A gap 87is provided between the frame seal 94 and the dividing plate 96.

Referring to FIGS. 27, 29, 30-32, 37-41, and 43-49, the humidifier tub20 may also include a water level indicator 102. The water levelindicator 102 may be provided on the dividing plate 96 of the flow plate84. As shown, for example, in FIG. 39, the water level indicator 102 mayhave a generally polygonal perimeter, including a generally rectangularportion 175 and a generally triangular portion 177. It should beappreciated, however, that other perimeter shapes may be provided forthe water level indicator 102, including regular polygonal shapes (e.g.square, rectangular, pentagonal), or polygonal shapes that arecombinations of regular polygonal shapes, or polygonal shapes combinedwith curvilinear surfaces.

As shown in FIGS. 31, 37, 39, 41, 43, 45, 46 and 49, the water levelindicator 102 comprises a drain hole 104 to allow the water to drain outof the bottom of the water level indicator 102 to the tub base 82. Asshown, for example, in FIG. 49, the drain hole 104 is not provided atthe bottom of the water level indicator 2, but is located at anintermediate position between the bottom and the top of the water levelindicator 102 to allow any pooled water to drain away from theintermediate position. In this embodiment the water level indicator 102is not filled with water but the water level is indicated against thesloping surface of the water level indicator as described in more detailbelow. As shown in FIG. 37, the drain hole 104 is located at a positiongenerally corresponding to the plane of the dividing plate 96 of theflow plate 84. As also shown in FIG. 37, and FIGS. 31, 38, 39, 41, 43,45 and 46, the water level indicator 102 may include indicia 103 thatindicates a maximum fill level of the humidifier tub 20. As shown in thefigures, the indicia 103 may be provided at the same level of the waterlevel indicator 102 as the drain hole 104.

Referring to FIG. 49, the generally triangular portion of the waterlevel indicator 102 extends below the frame seal 94 into the tub base 82when the tub is in the assembled condition and includes a first angledwall 109 and a second angled wall 111. As the water level of the tubbase 82 increases during fill up, the water level will initially contactthe bottom of the water level indicator 102. As the water levelcontinues to increase, the second angled wall 111 directs the waterlevel toward the drain hole 104 and the indicia 103 which are providedin the angled wall 111 between the frame seal 94 and the dividing plate96 of the flow plate. As the water level continues to increase andapproaches the drain hole 104, the visibility of the water levelrelative to the indicia 103 increases. As the indicia 103 is provided atthe same level as the drain hole 104, the maximum fill level of the tub20 is detected when the water level reaches the level of the drain hole104 and the indicia 103.

Referring to FIGS. 33, 35, 42 and 48, the seal 112 may be provided onthe periphery of the wedge 114 of the bridge 100. The wedge 116 of thetub lid 86 is configured to engage the wedge 114 of the dividing plate96 of the flow plate 84 to force the seal 112 between the rim 118 of thetub base 82 and the latch 130 of the tub lid 86. As shown in FIG. 48,the wedge 114 may comprise a flange 105 around its perimeter thatincludes a slot 107 that is configured to receive a portion of the seal112, as shown, for example, in FIG. 33.

Humidifier Tub—Disposable—Third Embodiment

Referring to FIGS. 50-62, a humidifier water tub 20 is configured to bedisposable according to still another sample embodiment as illustrated.The humidifier tub 20 comprises a tub base 82 and a tub lid 86. The tublid 86 includes an oval opening 300 and a sump region 340 that surroundsthe outlet 92 of the channel 90 that is formed in the tub lid 86 todirect the flow of air from the flow generator to the water contained inthe tub 20. The sump region 340 facilitates filling the tub 20 byproviding a larger area for entry of water than the outlet 92 of theflow channel 90.

The tub lid 86 also comprises a cover portion 301 that covers thesection of the flow channel 90 from the flow generator 12 to the inlet98 of the tub 20 that is angled down towards the flow generator 12. Thecover portion 301 prevents any water from flowing back into the flowgenerator 12 if the tub 20 was filled with water while still connectedto the flow generator 12 as water may only be poured into the tub in theregion provided by the opening 300 which is designed to channel thewater down towards the outlet 92.

As shown in FIGS. 53-62, a water level indicator 320 may be provided tothe humidifier tub 20 that is visible through the window 30 of the lid18. The water level indicator 320 may comprise a base portion 307 and anangled portion 303 extending from the base portion 307. The angledportion 303 may include markings 304 to indicate various water levels.The angled portion 303 may also include indicia 311 to indicate amaximum water fill level.

The water level indicator 320 may be removably connected to the dividingplate 96 of the flow plate 84 by posts 305. The posts 305 may beinserted into apertures 309 in the dividing plate 96 of the flow plate84. As shown in FIGS. 60a-60c , the posts 305 may include latches 313that are resiliently moveable with respect to the remaining portions ofthe posts 305. The latches 313 may be provided at the ends of legportions 315 which are attached to the base 307 of the water levelindicator 320. The leg portions 315 may be connected by a cross member317, as shown in FIGS. 59, 60 b and 61.

The water level indicator 320, for example, the angled portion 303, maybe formed of a colored plastic material, for example yellow. The waterlevel indicator 320 may be, for example, translucent. When the tub 20 isfilled with water, the water level indicator 320 may appear to changecolor, for example appearing slightly darker or a greenish-yellowishcolor as the water level rises.

As shown in the figures, the water level indicator 320 may be a roundedD-shape, although it should be appreciated that other shapes may beused. It should also be appreciated that the water level indicator 320may be attached to the dividing plate 96 of the flow plate 84 bystructures other than the post 305 as shown and described in thedrawings. For example, the water level indicator 320 may be adhered tothe dividing plate 96, or the water level indicator 320 may beintegrally formed, for example molded, with the dividing plate 96 of theflow plate 84.

Humidifier Tub—Reusable and Cleanable—First Embodiment

Referring to FIGS. 63-67, a tub 20 according to another embodiment ofthe invention is configured to be reusable, and cleanable. The tub base82 comprises a plurality of clips 106 that are configured to engage andretain the tub lid 86 in connection with the tub base 82. A clip 108 isalso provided and comprises an aperture 110 to accommodate the outlet 88of the flow plate, as shown in FIG. 63.

The flow plate 84 is configured to be removable from the tub base 82 andit is not permanently secured to the tub base 82. As shown in FIGS. 65and 67, the bridges 100 of the flow plate 84 include a wedge 114 that isconnected to a seal 112. The seal 112 is forced into sealing engagementbetween a rim 120 of the tub lid 86 and the rim 118 of the tub base 82.The clip 106 is provided to clip the tub lid 86 to the tub base 82 withthe seal 112 secured in between in sealing engagement. A first portion124 of the clip 106 engages the tub base 82 up to the rim 118 and asecond portion 126 of the clip 106 is configured to engage a projection128 of the tub lid 86 to secure the tub lid 86 and the tub base 82 inengagement.

The humidifier 14 does not include any seals that are provided under thewater supply of the tub base 82. The lid 18 comprises the seal 19 toallow for pressurizing of the humidifier chamber 16 with the flowprovided by the flow generator 12 to reduce the pressure on the tubjoints, including the disposable tub and the reusable, cleanable tub,thus reducing leaks. Pressurizing the humidifier chamber also reducestolerances for insertion of the water tub with respect to seals on theinlet of the humidifier and the outlet tube 70 of the humidifier 14. Thesealing ring 76 provided to the outlet tube 70 is provided on an outersurface of the humidifier cradle 32 and not provided under the water ofthe supply contained in the tub base 82.

Humidifier Tub-Reusable and Cleanable-Second Embodiment

Referring to FIGS. 68-72, a water tub 20 according to another sampleembodiment is configured to be reusable and cleanable. The tub 20 mayhave a water level indicator 320 similar to the water level indicatordescribed with respect to the previous embodiments. It should beappreciated that the tub 20 may be provided with any of the water levelindicators described herein.

The tub lid 86 may include the cover portion 301 to cover the inletregion of the flow channel 90 adjacent to the inlet 22 of the humidifier14 that is connected to the flow generator 12.

As shown in FIGS. 68-72, the tub lid 86 may be secured to the tub base82 by a plurality of clips 106, 108. The clip 108 may have an apertureconfigured to accommodate the outlet 88 of the tub 20. The tub lid 86may include projections 128 that are received in apertures 129 in theclips 106. The tub lid 86 may also include projections 152 that arereceived in apertures 151 provided in the clip 108.

As also shown in FIGS. 68-72, the tub lid 86 may include recesses 330 toaccommodate the fingers of a user of the tub 20 to provide a spacebetween the tub lid 86 and the clips 106 as the user inserts the tub lid86 on to the tub base 82 so that the projections 128 are received in theapertures 129. The recesses 330 may also accommodate the fingers duringremoval of the lid 86 from the base 82, for example to allow the partsof the tub 20 to be disassembled and cleaned.

It should be appreciated that the reusable and cleanable tubs mayinclude a water level indicator as discussed above with respect to theembodiments of the disposable tub. It should also be appreciated thatthe reusable and cleanable tubs may include more than one water levelindicator as discussed above with respect to the embodiments discussedabove. It should further be appreciated that the water level indicator,or indicators, or the tub may not include indicia to include a maximumwater level.

Heated Tube

Referring to FIG. 73, a heated tube 134 is connectable to the outlettube 70 of the humidifier 14. The heated tube 134 comprises a cuff 136that includes a humidifier connector 138 that is configured to beconnected to the tube connector 50 of the humidifier 14. The humidifierconnector 138 comprises terminals 140 that are configured to receive thecontacts 78 of the tube connector 50 when the humidifier connector 138and the tube connector 50 are connected. The cuff 136 may be formed asdescribed, for example, in U.S. application Ser. No. 11/936,822, theentire contents of which are incorporated herein by reference. Theheated tube may include, for example, two or three wires and maytransmit and receive signals to and from a controller in the humidifierand/or the flow generator as described in U.S. application Ser. No.11/936,822. The end of the humidifier connector 138 that is configuredfor insertion into the tube connector 50 of FIG. 15 may include an angle200 to facilitate insertion of the connector 138 into the tube connector50. The angle 200 may be between about 15°-35°.

Referring to FIGS. 74-76, the heated tube 134 may be connected to apatient interface, e.g. a mask, by a cuff 142 provided at the end of theheated tube 134. An aerofoil fixture 144 is provided in the cuff 142 andincludes a thermistor 148, as shown in FIG. 75. The shape of theaerofoil fixture 144 provides a smooth flow around the aerofoil fixture144 so that the thermistor 148 provides a good reading of thetemperature of the flow of breathable gas in the tube 134. The cuff 142may be formed by, for example, overmolding on a pre-block 146, or anymethod disclosed, for example, in U.S. application Ser. No. 11/936,822.The thermistor 148 is connected to the wires in the heated tube 134 bylead frames 150. The temperature sensed by the thermistor 148 may beprovided as a signal from the thermistor 148 through the lead frames 150and the wires to a controller located in the humidifier and/or the flowgenerator.

The tube 134 may have a 15 mm internal diameter. The tube 134 may beheated using wires as described in U.S. application Ser. No. 11/936,822.A non-heated 15 mm air delivery tube my also be used. The 15 mm internaldiameter tube may be connected to the tube connector 50 and the patientinterface using a 22 mm isotaper connection.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention. Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. Further, each independent feature orcomponent of any given assembly may constitute an additional embodiment.Furthermore, each individual component of any given assembly, one ormore portions of an individual component of any given assembly, andvarious combinations of components from one or more embodiments mayinclude one or more ornamental design features. In addition, while theinvention has particular application to patients who suffer from OSA, itis to be appreciated that patients who suffer from other illnesses(e.g., congestive heart failure, diabetes, morbid obesity, stroke,barriatric surgery, etc.) can derive benefit from the above teachings.Moreover, the above teachings have applicability with patients andnon-patients alike in non-medical applications.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise,” “comprised” and “comprises” where they appear.

It will further be understood that any reference herein to known priorart does not, unless the contrary indication appears, constitute anadmission that such prior art is commonly known by those skilled in theart to which the invention relates.

1.-20. (canceled)
 21. A humidifier for humidifying a flow of pressurizedbreathable gas to be delivered to a patient, the humidifier comprising:a chamber comprising: a chamber base having a bottom surface and atleast one chamber side wall, the bottom surface having a heater plate,the chamber side wall having a chamber opening and a chamber wall sealsurrounding the chamber opening; a chamber lid being hingedly attachedto the chamber base and pivotably movable between an open position and aclosed position, the chamber lid having a chamber lid seal; and a lidclosure assembly to selectively lock the chamber lid to the chamberbase; and a tub configured to contain a supply of water, the tub beingremovably positionable fully within the chamber base, the tub configuredto receive the flow of pressurized breathable gas and output the flow ofpressurized breathable gas with increased humidity, the tub comprising:a tub base configured to contain the supply of water, the tub baseincluding a metal surface configured to contact the heater plate; a tubopening configured to communicate with the chamber opening, the tubopening being disposed on a tub side wall, the tub opening beingsurrounded by a substantially flat tub sealing surface; an at leastpartially inclined wall disposed opposite of the tub side wall; and atop surface having a proximate end adjacent to the tub side wall and adistal end adjacent to the at least partially inclined wall, the atleast partially inclined wall angled relative to the top surface andextending downwardly from the top surface toward the tub base, wherein:when the chamber lid is pivoted from the open position to the closedposition, the chamber lid seal contacts the top surface of the tub andcontacts the at least partially inclined wall.
 22. The humidifier ofclaim 21, wherein the lid closure assembly includes a lid openingmember, a spring and a lid latch, the lid opening member is slidablycoupled to the chamber base to move the lid latch between a lockedposition and an unlocked position, the lid latch is configured tomechanically engage a catch of the chamber lid in the locked position inorder to retain the chamber lid in the closed position, the springbiases the lid latch into the locked position, and the lid openingmember is slidable by the patient against the bias of the spring to movethe lid latch to the unlocked position, to allow the chamber lid to bemoved to the open position.
 23. The humidifier of claim 22, wherein thelid opening member is slidable in a first direction and wherein aconnection assembly configured to selectively connect the chamber to aflow generator is slidably coupled to the chamber base and slidable in asecond direction perpendicular to the first direction.
 24. Thehumidifier of claim 22, wherein the catch is disposed on an innersurface of the chamber lid, the inner surface configured to face thebottom surface of the chamber base in the closed position.
 25. Thehumidifier of claim 22, wherein the lid opening member is configured tomove along a direction parallel to a direction that the flow ofpressurized breathable gas is configured to enter the tub.
 26. Thehumidifier of claim 21, wherein the tub includes a front side, a rearside, and two lateral sides that connect the front and rear sides, thetub side wall being at or forming the rear side, and the at leastpartially inclined wall being at the front side; the front side, rearside, and two lateral sides are oriented perpendicularly to the chamberbase; and the chamber side wall is a vertical chamber side wall and isoriented perpendicularly to the chamber base.
 27. The humidifier ofclaim 21, wherein the tub further comprises a water level indicatorconfigured to indicate a maximum fill level for the tub base, andwherein the chamber lid includes a window configured to allow for visualinspection of the tub.
 28. The humidifier of claim 21, wherein thesubstantially flat tub sealing surface and the chamber wall seal form aface seal.
 29. The humidifier of claim 21, wherein the chamber furtherincludes connection assembly configured to selectively connect thechamber to a flow generator, the connection assembly comprising a plate,a spring, and a chamber latch, the plate is slidably coupled to thechamber base to move the chamber latch between a locked position and anunlocked position, the chamber latch is configured to mechanicallyengage a catch of the flow generator in the locked position in order toretain a connection between the chamber and the flow generator, thespring biases the chamber latch into the locked position, and the plateis slidable by the patient against the bias of the spring to move thechamber latch to the unlocked position, to allow the chamber base to bemoved relative to the flow generator.
 30. The humidifier of claim 29,wherein the connection assembly is slidable in a first direction andwherein the lid closure assembly slidably coupled to the chamber baseand slidable in a second direction perpendicular to the first direction.31. The humidifier of claim 29, wherein the chamber base furtherincludes a chamber plate an aperture sized to receive the chamber latchand allow the chamber latch to move between the locked position and theunlocked position.
 32. The humidifier of claim 21, wherein: top surfaceincludes a top opening is oriented in a substantially perpendiculardirection to the tub opening; the chamber lid seal sealingly engages thetop surface around the top opening when the chamber lid is in the closedposition; and the chamber lid seal biases the tub toward the chamberside wall when the chamber lid is in the closed position.
 33. Thehumidifier of claim 21, wherein: an outer sealing rim configured topressurize a volume of the tub base with the flow of pressurizedbreathable gas, wherein the outer sealing rim includes a substantiallyrectangular perimeter; an inner sealing rim disposed entirely within thesubstantially rectangular perimeter of the outer sealing rim, the innersealing rim including a substantially curvilinear perimeter; and whenthe chamber lid is pivoted from the open position to the closedposition, a vertically directed force and a laterally directed force areapplied against the tub, the vertically directed force being applied bythe chamber lid seal contacting the top surface of the tub, thus urgingthe metal surface of the tub base toward the heater plate, and thelaterally directed force being applied by the chamber lid sealcontacting the at least partially inclined wall, thus urging thesubstantially flat tub sealing surface into sealing engagement with thechamber wall seal.
 34. The humidifier of claim 21, wherein the chamberbase further comprises an electrical connector connected to a pluralityof wires, the electrical connector configured to engage a flowgenerator.
 35. The humidifier of claim 21, wherein the chamber side wallfurther includes at least one electrical contact configured to form anelectrical connection.
 36. The humidifier of claim 21, wherein the tubfurther comprises a tub lid having the substantially flat tub sealingsurface, the tub lid being permanently connected to the tub base, andwherein the chamber fully encloses the tub lid and the tub base when thechamber lid is in the closed position.
 37. A respiratory apparatuscomprising: a mask configured to be worn by a patient; the humidifier ofclaim 21; a flow generator removably connected to the humidifier via amechanical connection assembly and an electrical connection, the flowgenerator configured to generate the flow of pressurized breathable gas;and a hose removably connected to the chamber and to the mask, the hoseconfigured to covey the flow of pressurized breathable gas withincreased humidity from the humidifier to the mask.
 38. The respiratoryapparatus of claim 37, wherein the flow generator is configured toprovide electrical power and/or control signals to the humidifier; theflow generator includes a display configured to output an operationalstate of the flow generator; and the flow generator includes a knob forselectively controlling a function of the flow generator and/or thehumidifier.
 39. The respiratory apparatus of claim 37, wherein the hoseis electrically connected to the chamber, and wherein the hose isconfigured to increase in temperature as a result of the electricalconnection with the chamber.
 40. A humidifier for humidifying a flow ofpressurized breathable gas to be delivered to a patient, the humidifiercomprising: a chamber comprising: a chamber base having a bottom surfaceand at least one chamber side wall, the bottom surface having a heaterplate, the chamber side wall having a chamber opening; a chamber lidbeing removably attached to the chamber base and movable between an openposition and a closed position, the chamber lid having a chamber lidseal; and a tub configured to contain a supply of water, the tub beingremovably positionable fully within the chamber base, the tub configuredto receive the flow of pressurized breathable gas and output the flow ofpressurized breathable gas with increased humidity, the tub comprising:a tub base configured to contain the supply of water, the tub baseincluding a metal surface configured to contact the heater plate; a tubopening configured to communicate with the chamber opening; an at leastpartially inclined tub side wall; and a top surface having an endadjacent to the at least partially inclined tub side wall, the at leastpartially inclined tub side wall angled relative to the top surface andextending downwardly from the top surface toward the tub base, the topsurface having a top opening, wherein: when the chamber lid is pivotedfrom the open position to the closed position, the chamber lid sealsealingly engages the top surface around the top opening and contactsthe at least partially inclined tub side wall.
 41. The humidifier ofclaim 40, wherein the chamber lid seal has an asymmetrical shapeconstructed such that the chamber lid seal and the chamber lid may onlyattach in a single orientation.
 42. The humidifier of claim 40, whereincontact between chamber lid seal and the at least partially inclined tubside wall biases the tub in a lateral direction.
 43. The humidifier ofclaim 40, wherein the chamber further comprises a lid closure assemblyto selectively lock the chamber lid to the chamber base, wherein the lidclosure assembly includes a lid opening member, a spring and a lidlatch, the lid opening member is slidably coupled to the chamber base tomove the lid latch between a locked position and an unlocked position,the lid latch is configured to mechanically engage a catch of thechamber lid in the locked position in order to retain the chamber lid inthe closed position, the spring biases the lid latch into the lockedposition, and the lid opening member is slidable by the patient againstthe bias of the spring to move the lid latch to the unlocked position,to allow the chamber lid to be moved to the open position.
 44. Thehumidifier of claim 43, wherein the lid opening member is configured tomove along a direction parallel to a direction that the flow ofpressurized breathable gas is configured to enter the tub.
 45. Thehumidifier of claim 40, wherein the chamber further includes connectionassembly configured to selectively connect the chamber to a flowgenerator, the connection assembly comprising a plate, a spring, and achamber latch, the plate is slidably coupled to the chamber base to movethe chamber latch between a locked position and an unlocked position,the chamber latch is configured to mechanically engage a catch of theflow generator in the locked position in order to retain a connectionbetween the chamber and the flow generator, the spring biases thechamber latch into the locked position, and the plate is slidable by thepatient against the bias of the spring to move the chamber latch to theunlocked position, to allow the chamber base to be moved relative to theflow generator.
 46. The humidifier of claim 40, wherein the chamber sidewall further includes at least one electrical contact configured to forman electrical connection.
 47. The humidifier of claim 40, wherein thetub further comprises a tub lid having the top surface, the tub lidbeing permanently connected to the tub base.
 48. A respiratory apparatuscomprising: a mask configured to be worn by a patient; the humidifier ofclaim 40; a flow generator removably connected to the humidifier via amechanical connection assembly and an electrical connection, the flowgenerator configured to generate the flow of pressurized breathable gas;and a hose removably connected to the chamber and to the mask, the hoseconfigured to covey the flow of pressurized breathable gas withincreased humidity from the humidifier to the mask.